Facebook Share post thumbnail unavailable

I am having a similar problem with the facebook share button on the homepage (I have “include buttons in excerpts” enabled). Sometimes it will display the correct thumbnail image from the article, other times it will just display a random image from the homepage. Help?

I’m having this very same issue. It selects the main logo image from my wordpress site, or the authors photo, but not the image that goes with the post itself. Dumb.